The battery could very well be bad! Most batteries are reman. Who knows how long that battery has sat on the shelf.
The public is told car battery is maintenance free. We install the battery and forgot about it!
Far from the truth. Attention (charging) needs to be given to the battery from the start using today's modern smart charger.
I put my 1 year old battery on the charger every two months now. Using the smart charger will drain it down then charge the battery back up...this is a cycle.
Batterys don't have power stored in them but it contains all of the properties to produce the power. Those properties need to be refreshed from time to time. The best way to do that is to have the charger take the battery through a cycle.
I monitor my battery by way of...
How fast it turns over the starter.
Of course the age.
How well does the car distribute the power throughout the car. BMWs are hogs when it comes to use of power from the battery. But when a battery is getting low in power the car will start to select or prioritize what components should be powered most.
Keep in mind the BMW car is equipped with a (Hidden Menu) in the On Board Computer it has a feature that the user can check the power/voltage of the installed battery right there on the spot.
Its the truth...they don't call the BMW "the ultimate driving machine" for nothing!
Knowledge is key and remember BMWs don't like to sit especially for long periods of time.
They also don't like short trips (in town driving) this usually doesn't give the alternator enough time to charge the battery back to full or back to the starting point of that day.
Resulting in a lesser charged battery day after day.
Now you see why I'm charging my battery once every 2 months.

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